PPM going up extremely over night

Discussion in 'Hydroponic Growing' started by vick.sarkis, May 29, 2019.

  1. I just setup 2 DWC systems and wanted to run a test between 2 liquid nutrients, General hydroponics flora series and pure blend pro grow.

    I added the suggested amounts from the back of the bottles just to keep the test even and added Cal-Mag 3ml per gallon 10 gallons)
    when finished i got a ppm of

    Flora series 781
    pure blend 777

    today i went out to check and see how things are moving along and for some reason the ppm for both have gone up by a substantial amount.

    flora series now is about 1100 ppm
    and pure blend is about 980ppm

    I tested my meter in my other NFT systems and its reading the correct amounts so the tester is not at fault and the PH for both is at about 6.
  2. Im no hydro guy but im guessing the plant took H20 out
  3. that would make sense but there is only 6 (2 week old ) plants in it, barley have any roots so im guessing this isnt the issue. Its just so surprising that it happened to both DWC tots. Both are 10 gallon and identical next to each other.
  4. There should be an a pretty easy answer to this, how much did your water level drop?
  5. Your plants drank the water out not the nutes

    Sent from my iPhone using Grasscity Forum

  6. This explains it in 2 minutes.
    • Agree Agree x 1
  7. the water level barley moved. The plants are about 14 days old, very little and only 6 of them. So not much water being used by them.
    Is it possible both nuts where not mixed all the way and dissolved more over night? thats the only thing i can think of.
  8. I think you are understanding how much plants drink. At the end of a month veg mine and taking in about 3-5 gal of water per plant per day. 3 hitting veg in a 10 gal is a small tank.
  9. start with fresh batch of water and start low with ppms if it too low you can always add check over fewdays and see whats going on i bet it too strong how roots look
  10. 200-300 ppms .700 scale
  11. 200 ppm .500 scale .2-.5 EC
  12. whats ph doing going down?
  13. sorry guys for the late reply.
    I just checked both DWC tots and here are the results from today.
    Flora series PPM 985 / PH 6.24
    Pure Blend PPM 935 / PH 6.6

    Looks like the ppm is dropping and the little plants look healthy. I will keep updating here with my daily ppm and ph readings if you guys are interested.
  14. Your ph is a bit high for dwc. I like to drift 5.6-6.0.
    • Agree Agree x 1
  15. I agree with Gelato. The PPM's now dropping is a good sign though. How long did you wait to take the ppm readings the day before they exploded up? Sometimes, depending on overall res size and circulation, it can take a little while for the ppm's to stabalize. But if your plants are happy, then they're happy...that's all that matters. :) I'm excited to see the end result of your experiment!
  16. The Cal-Mag will react with the other nutrients.
    Electrical ppm meters are actually reading the conductivity of the solution.
    Not all salts conduct equally.
    I did some experiments some years back and tested the accuracy of the meter I was using, actually I used 2 meters to compare, but the results were close.
    Calcium Nitrate that was actually 500ppm read 270ppm
    Potassium nitrate actual 500ppm read 325ppm
    Sodium Chloride actual 500ppm read 507ppm
    As you can see they were calibrated to ordinary salt.
    Anyway when you mix all the various chemicals together trying to accurately measure ppm is almost impossible out side of taking a sample evaporating the water and weigh the remaining salt.
    These days I find out at what EC the plant likes and read the recommended dosage on the bottle if I'm using consumer nutrients. I don't add any additives anymore.
  17. You shouldn't really need to measure the ppm's of each added nutrient unless you are adding each nutrient individually. As long as you're using a good, complete base nutrient, and calmag if it comes to be needed, you should be fine just measuring ppms/EC. Of course, account for ppm's in your water before nutes, and account for how many ppm's the calmag adds to it.
  18. I always mix nutrients with water and let them sit overnight, then add to the system, or prepare the grow tank a few days in advance of planting. As you guessed, your chemicals were breaking down and reacting with each other, causing a PPM increase.

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